The present invention relates to a motion sensor that optically detects hand movements and the like.
For example, Japanese Patent Laid Open Publication No. H10-148640 describes a hand gesture detection device wherein, a device for optically detecting hand gestures comprises: a plurality of light emitting elements that emit lights having differing characteristics in a hand gesture region; a light receiving element that receives light reflected from a hand, resulting from the light emitted from the light emitting elements; and a detector that detects the movement direction and movement velocity of hand gestures on the basis of changes over time in the differences and sums of the amount of reflected light received by the light receiving element, from the hand, resulting from the light emitted from the light emitting elements.
With the hand gesture detection device described in Japanese Patent Laid Open Publication No. H10-148640, it is possible to detect the movement direction and the movement velocity of hand gestures and, for example, while driving an automobile, it is possible for the driver to adjust the volume of a car stereo, or adjust the temperature of the air conditioner or the like, without looking at the instrumentation.
Furthermore, Japanese Patent Laid Open Publication No. 2008-172336 describes a photoelectric sensor comprising: a light receiving element that receives light wherein pulsed light incident from a detection region is biased by DC light; a first projection element that projects pulsed light towards the detection region; and a second projection element that projects DC light directly toward the light receiving element.
With the photoelectric sensor described in Japanese Patent Laid Open Publication No. 2008-172336, by providing a light source that irradiates the light receiving element with direct light (second projection element) is possible to improve the response time of the photoelectric sensor.
However, with the hand gesture detection device described in Japanese Patent Laid Open Publication No. H10-148640, there is a possibility of errors if the light receiving element is irradiated with direct light from a plurality of light emitting elements, and no countermeasure for the same is set forth. Furthermore, because this is directed to operating a car stereo or air conditioner, there is no need for the sensor to have a rapid response speed, and thus no particular consideration is given to improving sensor response speeds.
Furthermore, with the device described in Japanese Patent Laid Open Publication No. 2008-172336, while consideration has been given to sensor response speeds, there is basically only one first projection element that projects pulsed light toward the detection region, and therefore the configuration will not detect the movement direction and movement velocity of the hand gesture. Furthermore, there is a risk that light leaking, from the light source that serves for irradiation with direct light, into the detection region, will be reflected by the detection object, and this reflected light will be detected by the light receiving element, resulting in an error, but no countermeasure for the same is set forth.